Tornado warning: El Nino could spawn more deadly twisters

November 3, 2009|By Willoughby Mariano, Sentinel Staff Writer

Brace for tornado season. This winter, it may be especially ugly.

The weather phenomenon known as "El Niño" is warming waters in the Pacific Ocean, a sign that severe storms capable of spawning killer tornadoes could batter the Orlando area in the coming months, forecasters with the National Weather Service warn.

The state's two deadliest twisters struck during years when El Niño was in effect, and both of them ravaged Central Florida: the February 1998 tornadoes that killed 42 people, and the February 2007 storms that killed 21.

"I think the bottom line is you always have to have a tornado plan, but in an El Niño year … if tornado watches come out, you really need to pay attention," said Bart Hagemeyer, meteorologist in charge at the National Weather Service in Melbourne.

Here's what you need to know:

Why does El Niño spawn deadly tornadoes in Florida?

When the jet stream moves south, it pulls severe weather it helps spawn along with it.

Since the winds of the jet stream blow from west to east, they travel over the warm, moist air over the Gulf just before arriving in Florida. This moisture and heat strengthen the jet stream's ability to create rough storms, bringing severe weather to the state.

El Niño tornadoes can be especially deadly because they tend to form in the middle of the night, when people are asleep and cannot hear warnings to take cover.

How reliable is this year's tornado prediction?

Rough tornado seasons are easier to predict than bad hurricane seasons, Hagemeyer said. The forces that create deadly twisters — such as the position of the jet stream and the direction of the wind — are generally well-understood. The development of hurricanes, however, relies on far more factors, many of which meteorologists are still working to understand.

Research shows El Niños have spawned rough weather to Florida for as long as state weather records have been kept. Seven of the state's 10 most deadly tornado days took place in what experts think are El Niño years. Four of them struck the Interstate 4 corridor.

Other El Nino years brought storms that dropped more than a foot of hail or six times the average amount of rain.

How do I keep my family safe?

Have a plan. Know where you will go if a storm strikes.

Get a programmable National Oceanic and Atmospheric Administration weather radio and a backup pager or cell phone to receive weather updates.

Play close attention to forecasts. Storms that are likely to spawn tornadoes can be predicted days in advance.

If you live in a manufactured home or other housing that's vulnerable to high winds, stay with a friend or relative who lives in a sturdier house if strong storms are predicted overnight.